About salbutamolbeta2-adrenergic agonist, phenethylamine derivative, bronchodilator(antiasthma), uterine relaxant.mechanism of action of salbutamolsalbutamol is a short acting ?2 receptor agonist. it selectively stimulates ?2 receptors present in airway, uterus, and vascular smooth muscles. it directly relaxes the airway smooth muscles and produces bronchodilation. stimulation of ?2 receptors activates gs adenylyl-cyclase -cyclic amp path way and produces reduction in smooth muscle tone. ?2 receptor agonists also increases the conductance of large ca2+sensitive k+ channels in airway smooth muscles and leads to membrane hyperpolarisation and relaxation of smooth muscles. ?2 receptor agonists also suppress the release of leukotrienes and histamine from the mast cells in the lung tissue and enhance mucociliary function and decrease micro vascular permeability and also inhibits phospholipase a2 which produces inhibition of prostaglandins production.